Scribbled notes found by the Inquisitor while searching the Villa Maurel reveals that Carroll has joined the Red Templars, and has attained the rank of 'Knight-Captain'. Carroll is in charge of relations between the Red Templars and the Freemen of the Dales; deserters from the Imperial Army being used to advance the Elder One's agenda.

After wiping out the Freemen's leadership, the Inquisition poses as a group of Freemen attempting to re-establish contact with their Red Templar sponsors. As the officer in charge of the operation, Carroll travels to the meeting at Lion's Pavilion in the Emerald Graves, where he is slain in battle with the The Inquisitor and their comrades.

During the Precious Metals side quest, if you ask Godwin about why he needs so much lyrium, he will state that a number of the templars in the Circle Tower are developing side effects from lyrium addiction, and will mention Carroll specifically as an example.

At some point prior to the events of Inquisition, Carroll had wandered away from Kinloch Hold to the High Reaches near Minrathous. In his lyrium-addled state he thought he was hunting maleficars with his fellow templars, particularly with Knight-Commander Greagoir; in fact he inadvertently aided a Qunari beresaad in tracking down a rogue Tal Vashoth with twelve Saarebas.[1]